A big thank you to the Training and Behavior Dept of Oregon Humane Society for their help with cat body language information. WHISKERS Pupils, ear positions, body weight, and tails are the other indicators of how a cat is feeling.
Kitty Speak - this is interesting. some people believe that because cats have different "tail" language than dogs this is the reason for their feuding. But when a dog is raised as a young pup with cats, he learns cat "tail language".